1. Field of the Invention
This invention relates to a packaging technique for pressure transducers and, more specifically, to such packaging for pressure transducers capable of measuring high pressures in the range of up to about 5000 psi.
2. Brief Description of the Prior Art
Pressure sensors containing pressure transducers are well known, typical such systems being described in Pat. Nos. 4,716,492 and 4,774,626.
Pressure transducers of the prior art have generally been fabricated by providing a pressure sensing module in the form of a variable capacitor responsive to pressure which abutted an electronic circuit. The electronic circuit sensed the capacitance of the capacitor and provided an output through a plastic electrical connector indicative of the sensed pressure. The transducer elements were arranged such that a metal cup assembly having an opening or pressure inlet at one end thereof to receive the fluid under pressure to be measured also included therein the pressure sensing module which was separated from the inlet by a gasket, the electronic circuit and connector also being contained within the metal cup. The parts were held together within the metal cup by crimping the metal cup over the plastic connector, the latter being used as a support member.
The above described pressure transducer provided highly satisfactory results when operated in the low to moderate pressure ranges of up to 500 to 600 psi. However, when subjected to pressures at the pressure inlet in the range of about 3000 to 5000 psi and up, the above described pressure transducers tended to fail. There were several points of failure, these being from the inability of the plastic connector to support the high pressures to which it was being subjected. More specifically, the crimp at the metal cup was unable to retain the electrical connector crimped thereunder with the result that the connector was moved out of the cup and caused a failure of the transducer. A further point of failure was the plastic connector itself which would tend to shear or compress and release the gasket under the high pressure and release the gas under pressure. It is therefore clear that the prior art pressure transducer of the type described hereinabove was incapable of reliable operation in the high pressure environment.